A conventional scroll compressor is shown in, for example, Japanese Patent Publication 62-282186 (unexamined), in which a fixed scroll is positioned stationarily in a sealed container and an orbiting scroll is orbitally moved around a center of the fixed scroll.
However, in the conventional scroll compressor, a driving shaft of the orbiting scroll is cantilevered, with the result that a large vibration is generated particularly in a scroll compressor for high speed purposes. Further, in a large scale compressor, a larger centrifugal force of the orbiting scroll is produced, increasing the load applied to the bearing of the orbiting scroll. Consequently, there are possibilities of a reduction in the efficiency and reliability of operation.
A high speed scroll compressor is disclosed in Japanese Patent Publication 57-49721 (examined), in which two scrolls are rotated, and one of the scrolls is orbitally moved around the other scroll.
This high speed scroll compressor has some serious problems. For example, since the orbiting scroll is orbitally moved around the driving shaft, the orbiting scroll is possibly vibrated abruptly and violently, with the result of a failure in normal high speed operation, with abnormal sounds. Additionally, the two scrolls are rotated in the same direction by employing a coupling ring and a projection formed on an outer circumferential end of a spiral wrap so that a compression space formed by the spiral wraps of the two scrolls is reduced in volume involutely from the outer position to the inner position. Consequently, the structure becomes complex.
In the scroll compressor disclosed in aforementioned Japanese Publication 62-282186, an eccentric bearing for the orbiting scroll is spring-pressed by a resilient member to maintain a radial gap constant between the spiral wrap of the fixed scroll and the spiral wrap of the orbiting scroll so that a predetermined refrigeration capacity can be maintained. However, the eccentric bearing which receives a pin of the orbiting scroll, is pressed by the resilient member and at the same time inserted into a groove of an associated crank member. Accordingly, the orbiting scroll is influenced by the centrifugal force of its own rotation and the spring force of the resilient member. Consequently, there is a serious problem in that the pressure of the orbiting scroll against the fixed scroll becomes excessively large.